Clarifying the mechanism of triplet–triplet annihilation in phosphorescent organic host–guest systems: A combined experimental and simulation study

L. Zhang, H. van Eersel, P.A. Bobbert, R. Coehoorn

Chemical Physics Letters 652 (2016) 142–147

At high brightness, triplet–triplet annihilation (TTA) reduces the efficiency of organic light-emitting diodes. Triplet diffusion may considerably enhance this effect, which is otherwise limited by the rate of long-range interactions. Although its role can be clarified by studying the emissive dye concentration dependence of the TTA loss, we demonstrate here the practical applicability of a more direct method, requiring a study for only a single dye concentration. The method uses transient photoluminescence yield measurements, for a wide initial excitation density range. The analysis is applied to an iridium complex and is supported by the results of kinetic Monte Carlo simulations using Bumblebee.